Originally Posted by BennyBoy
video shows him using it on the bore, would it be bad to use it on inside of airsoft barrel too?
You mean the Frog Lube video?
It's supposedly a "CLP" ... "Cleaner Lubricant Protectant". I don't see it doing the "C" well in the video, (heck the guy recommends using something else too) so I doubt it does the other two letters any better.
Also, while yes people apply oil (sometimes grease for long term storage) inside a barrel, it will increase chamber pressures enough that you're told to remove any excessive lubricant first by most manufacturers and shooting manuals. A very light coating is fine, but running a dry patch before shooting is recommended.
It's like putting grease or oil on your car's transmission input shaft so the clutch disk moves "freely", sure it's a good idea, except it's not good for what is going on around it.
Think about how little oil is actually going down the barrel of a GBB from the 2 drops per 9 magazine fills, and then factor in how much it really is per shot. It's pretty tiny amount of oil that is recommended in a GBB.